The present invention relates to a joystick and, in particular, relates to a compact joystick in which an arm member has a wall thickness suitable to strengthen and improve the durability thereof.
Joysticks disclosed in the related prior art will be explained with reference to FIGS. 7 and 8. In the figures, a joystick 1 is configured in a manner that the arms 3 and 4 being orthogonal to each other in the vertical direction are disposed so as to rotate freely within a casing 2. Each of the arms 3 and 4 is pivotally supported at both end portions thereof by the casing 2. The one end portions of the arms 3 and 4 are connected to variable resistors 5, 6 serving as signal output units, respectively.
Long holes 7, 8 extending in the longitudinal directions of the arms 3, 4 are opened at the center portions of the arms 3, 4, respectively. An operation stick 9 serving as an operation stick is provided so as to pass through the long holes 7, 8. The lower end portion of the operation stick 9 is formed as a convex-shaped spherical portion 9a. A concave-shaped spherical portion 10a is formed at the center portion of the base 10 of the joystick 1. The convex-shaped spherical portion 9a is disposed at the concave-shaped spherical portion 10a so as to rotate freely. A knob (not shown) is fitted into the upper end portion of the operation stick 9.
When the operation stick 9 is operated, the operation stick 9 rotates around the concave-shaped spherical portion 10a serving as a rotation fulcrum, then the operation stick 9 rotates the arms 3 and 4 thereby to rotate the variable resistors 5 and 6 coupled to the arms 3 and 4, so that the variable resistors 5 and 6 generate outputs according to the operation of the operation stick 9.
Further, as shown in FIG. 8, the operation stick 9 of the joystick 1 has shaft portions 11 protrusively provided at the left and right portions of the lower portion thereof, respectively. The shaft portions 11 are fitted into shaft holes 13, which are formed at the center portions of inside wall portions 12, 12 forming the long hole 8 perforated at the lower arm 4, in a pin-coupling method so as to rotate freely, respectively. Then, the operation stick 9 and the arms 3, 4 are fixed in the vertical direction. In order to hold the arms 3, 4 at the neutral portions, a coil spring 15 is disposed between the base 10 and a ring-shaped supporting member 14 which is largely perforated at the center portion thereof abutting against the lower face of the lower arm 4 and has a reverse-U shape in its section.
However, according to the related compact joystick, the shaft portions protrusively provided at the lower portion of the operation stick are forcedly inserted and fitted into the shaft holes perforated at the lower side arm so as to rotate freely.
Thus, when a user operates such a compact joystick heavily, an intense force acts on the arm which tries to restore to the neutral position due to the coil spring. In particular, a more load is applied to the arm near the shaft portions of the operation stick due to a load applied from the upper side and action of a lever. Thus, the arm deforms due to the load and so the durability of the joystick is remarkably degraded. Such a phenomenon appears remarkably in the case of a compact joystick formed by processing plastics.